Hey, I've noticed that default result for Iron Man 3 (68721) has spanish title and original_title, which is wrong by itself IMO, but a bigger problem is that I can't seem to get US title, alternative_titles is empty?
It looks like this was already changed: https://www.themoviedb.org/movie/68721-iron-man-3/changes
Keep in mind the API caches data for ~24 hours so you won't see the changes be reflected on the API right away. I also went ahead and locked the original and english titles so this won't be able to happen again.
With regards to alternative titles, there aren't any entered.